Department of Veterinary Medicine

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Author: search.filters.author.Nan, YuchenSubject: search.filters.subject.Hepatitis E virus

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    A Linear Surface Epitope in a Proline-Rich Region of ORF3 Product of Genotype 1 Hepatitis E Virus
    (MDPI, 2016-08-18) Yang, Yonglin; Lin, Shaoli; Nan, Yuchen; Ma, Zexu; Yang, Liping; Zhang, Yanjin
    Hepatitis E virus (HEV) is one of the viral pathogens causing hepatitis in humans. HEV open reading frame 3 (ORF3) encodes a small multifunctional protein (VP13), which is essential for HEV infection. In this study, a linear epitope was identified in a polyproline (PXXP) motif from VP13 of genotype 1 HEV by using a monoclonal antibody. The epitope was detected in enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluorescence assays. Epitope mapping showed that the epitope locates in a proline-rich region containing a PXXP motif in amino acid residues 66-75 of VP13. The epitope was also detected in HEV-infected liver cells and reacted with genotype 1-specific antibodies in an HEV-positive human serum sample. The results demonstrated that the epitope in the PXXP motif of the genotype 1 VP13 is linear and surface-oriented, which should facilitate in-depth studies on the viral protein and HEV biology.
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    Interferense of Host Innate Immune Response by Hepatitis E Virus
    (2014) Nan, Yuchen; Zhang, Yanjin; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The host antiviral innate immunity mainly relies on host pattern recognition receptors (PRR) and downstream interferon (IFN) signaling. Host PRR for RNA viruses include Toll-like receptors (TLR) and Retinoic acid-inducible gene I (RIG-I) like receptors (RLR). Activation of both TLR and RLR pathways can eventually lead to the secretion of type I IFNs, which can modulate both innate and adaptive immune responses against viral pathogens, including hepatitis E virus (HEV). HEV causes acute hepatitis in humans and has been responsible for several outbreaks of hepatitis across the world. Currently, no commercial vaccine is available for the prevention of HEV infection in any country except China. HEV biology and pathogenesis as well as its responses to host innate immunity are poorly understood, though other hepatitis viruses, including the hepatitis A, B and C viruses, have been much better studied. In this study, how HEV interferes with IFN induction and IFN-activated signaling had been examined. Results showed that the protein encoded by HEV ORF1 can inhibit type I IFN synthesis and downstream JAK/STAT signaling pathway. However, the HEV ORF3 product is able to enhance RIG-I-mediated signaling to a certain extent. These data suggest that HEV proteins interfere with the host innate immune response and may exert the diverse roles depending on the stage and/or context of infection. These studies contribute to a better understanding of HEV pathogenesis and may facilitate a strategy development for the prevention and control of HEV infection.